Surgical mallet



Feb. 20, 1951 I J. J. NEFF ETAL 2,542,595

SURGICAL MALLET Filed Feb. 17, 1948 46 ATTORNE V5 Patented Feb. 20, 195,1

UNITED STATES PATENT OFFICE,

Joseph J. Neff, Los Altos;v and Frank I. Fuller, PalomAlto, Calif. Y

Application February 17, 1948, Serial No. 8,977

' 6 Claims. l This invention relates generally to surgical mallets such as are used for dental and bone surgery.

In the past it has been proposed to use electrically energized surgical mallets or impactors to take the place of the conventional manualtype mallet and surgical tool. Insofar as applicant can determine such electrical surgical Vmallets have not been satisfactory and have not been used in practice to any substantial extent. `fThis is attributed to a number of inherent disadvantages. For example the prior devices have not afforded suicient flexibility of control over the impacts r blows appliedeto thetool. In addition they have relied upon electricalv contacts formak'- ing and breaking an electrical energizing circuit. vSuch contacts are unreliable and make itdiiiicult to secure proper control over both the intensity and frequency of the impacts applied. f' In general it is an object of the present'invention to provide a surgical mallet ofthe eli-c-v trical type which will be vhighly practical and convenient to the operator, and which in gen# eral will avoid the disadvantages of prior electrical mallets. l

An additional object of the invention is 'to provide a surgical mallet which avoids the use of electrical contacts for making andbreaking an electrical energizing circuit.

A further object of the invention is to provide a device of the above character which is automatically inactive to apply impacts to the tool except when the operator is using the tool. In this connection the present device is lcharacterized by an arrangement which retains the blow imparting member of the .device inactive except during periods when the tool lcarried by the device. is being pressed against the work.

I'Another object of the invention is to provide apparatus of the above character having elec-- tronicpulsing means for energizing thesaine.

Another object of the invention is to-provide a novel type ofV electronicpulsing means which is adjustable as to frequency and intensity of the generated pulses.

Further objects of the invention will appear from the following description in-which the preferred embodiment has been set forth in detail in conjunction withthe accompanying drawing.

Referring to the drawing: n

Figure l-is a diagrammatic view illustrating apparatus-incorporating the present invention.

Figure 2 is a side elevationalview in section' illustrating an electrical surgical mallet incorporating the present invention. Y

Figure 3 is a side elevational detail'in section;

(ci. :i2-53) illustrating certain parts of the .device in a diff ferent operating position from that shown in Fig` ure 2.

Figure 4 is a wave form curve illustratinglth wave kform of current supplied by the pulse gen,- erator. n l

Referring irst to Figure l of the drawing, we have shown a device I0 constructed in accordance with our invention, and electrically connectedv to the pulse generating means I I. The pulse gene;-- ating means is adapted to produce unidirectional electrical pulses recurrently, and at a frequency which can `be adjusted or controlled by Ythe op.- f

erator. The device IB is of such size and shape thatV it can be readily held in the handof anQop erator. and used in such operations as dental surgery, bone surgeryor the like. The device I Il as illustrated in. Figure 2 com.- prises a body or housingv I2 which is elongated as to form, and which serves to carry and enclose the working parts of the device. For convenience the body is made of a plurality of'parts, including the end part I2a which has threaded engagement I3 with the cylindrical shell part I2b, and the tapered portion I2C which hasva threaded connection I4 with the other vend of part |217.

Extending longitudinally within the shell lpart I2b, there is a sleeve I5 which is of .non-magnetic material, and Ywhich has collars I6 and I'I mounted upon its ends. A magnetic winding or solenoid coil I8 is .disposed about the sleeve I5. Sleeve I5 forms a longitudinally extending bore I9, Within which the metal plunger 2! is slidably tted. This plunger is formed of magnetic material such as steel, and forms a part of the mag-l netic field of the solenoid coil as will be presently explained. e

Near therear endY of the device a liner 22 is fitted within the shell part I2b, and serves toggether with vthe closure disc 23 and collar I'I, to form aterminal space 24 in which electrical'connections can be made.V Y, p A exible insulated `electrical cord 26 extends through an openingv 21 in the part I2a and the ilexible tubular conductorl 28 of this cord is grounded to the metal parts of the device by con'-` vnection to the metal disc 23. The central conductor 3| of the cord'extends into the space 24 and is electricallyjconnected to the metal-ten minal pin 32*l vThis terminal pinis mounted within-an insulating bushing and is electrically con-- nected to one terminal wire leading from'the solenoid coil I8.- The other terminal of 1thecoil I8 .iis electrically grounded to the metal pa'rtsfof` the device and .is thus electrically connected to the conductor 28.

Mounted between the collar I'I and the closure disc 23, there is a metal block 33 which provides a stop shoulder 34 for engagement with the adjacent end of the plunger 2|.

Adjacent the forward end of the solenoid coil I8, there is a member 36 which can be retained in place by threaded engagement 3'| with the shell part I2b, as illustrated. Member 36 has a rearwardly extending portion 38 of annular cross section, which ts within the forward end of the sleeve I5. As will be presently explained the rear end face of portion 35 forms an abutment stop adapted to be engaged by the forward end of plunger 2|. It is desirable in this connection to form the rear end face 39 of portion 38, and also the cooperating forward end face 4I of the plunger 2| substantially conical shaped as illustrated. Member 36,V together' with the shell part |2b and the colla-r 'I, is likewise formed of magnetic material such as a suitable steel,` to form together with the magnetic plunger 2i a eld or magnetic ilux path for the solenoid coil. It will be noted that the magnetic field is closed when the plunger 2| is moved downwardly into engagement with the portion 38, as illustrated in Figure 3.

The body part |2c of the device is provided y with a bore 42 in alignment with the axis of the elements as for example a tetrode thyratmn of solenoid plunger 2|, and the solenoid coil. A rigid rod 43 is slidably iitted in bore 42, and forms what can be termed an impact transmitting member. The forward end of member 43 is provided with a mounting 44 for a chisel or other type of tool 46. Mounting 44 can be of the collet type including a rotatable ferrule having threaded engagement 48 with the exterior end of the member 43. The end portion 49 is split and provided with a socket 5| for receiving the shank end of the tool.

In order to provide suitable means for preventing rotation of the member 43, its inner end is shown provided with a laterally extending pin 52, the ends of which are slidably accommodated within the slots 53. These slots are formed in a guide sleeve 54, which is mounted to or formed integral with the body part I2C.

Spring means is provided for urging the member 43 downwardly as viewed in Figure 2, and also for urging the solenoid plunger 2| upwardly. It is preferable to use a single coiled compression spring 56 as illustrated. This spring extends through the axial bore 51 formed in the member 35, with its one end seated upon the adjacent end of the member 43, and its other end seated upon an annular shoulder 58 formed within the plunger 2|.

v Means are provided whereby when the solenoid coil is energized to cause the plunger' 2 I to move downwardly Ias viewed in Figure 2, an impact or blow is imparted to the member 43 and thus transmitted to the tool 46. Thus a hardened steel pin 8| is'mounted in the forward end of the plunger 2| and is adapted to strike the end of a hard metal pin or button 62 mounted upon or forming the end of the member 43.

The parts described above are proportioned whereby the member 43, together with the tool mounting 44 and the tool 48 has limited permissible sliding movement axially of the device and between what may be termed projected and re* tracted limiting positions. The forward limiting position is determined by engagement of the pin 52 with the ends of slot 53 (see Figure 2).

Gil

The retracted limiting position is determined by engagement of pin 52 with the end face 63 provided on the member 36. The first limiting position of the plunger 2| is as is illustrated in Figure 2, and is determined by engagement of the rear end face of the plunger with the shoulder 34. The second limiting position of plunger 2| is determined by engagement between the forward end of plunger 2 I, and the rear end of portion 38, or in other words by physical contact between the surfaces 39 and 4|. Spring 56 serves to normally urge the plunger' toward the iirst named limiting position, and also serves to urge the member 43 toward its projected position. When the plunger 2| is in its second limiting position (see Figure 3) the opposed ends of the pins BI and 62 are in contact.

Various types of electrical pulse generators can be used with the device described above. The generator should supply unidirectional spaced recurrent pulses at a desired frequency, and it is desirable that the frequency be subject to adjustment at the will of the operator. Likewise it is desirable to permit adjustment of 'the intensity of the pulses, to thereby adjust the intensity of the impacts. The electronic type of pulse generator illustrated` in Figure 1 has been found desirable and satisfactory. It consists of a suitable gas filled tube 68 having plate, control and cathode the type known by manufacturers speciications as No. 2D2l. The plate 81 of this tube is shown connected to the cathode 68 of a two-way rectifier tube 69. This tube can be one of the type known by manufacturers specifications as 6X5. The two anodes 'II and 12 of rectifier tube 69 are connected to the terminals of the transformer secondary 13. Theprimary 'I4 ofl this transformer can connect with a stardard IIil volt a1-l ternating current supply line. The cathode I6 of tube 66 is connected by conductor Il to the midpoint of secondary winding 13, in series with the resistor 18. The screen grid I9 of the tube 66 is shown conductively connected to the cathode 16. A resistance-capacitance circuit serves to time firing of the tube 6B. This circuit includes the series resistors 82 and 83, connected between the conductor 'Il and conductor 84. Resistors 82 and 83 are shunted by the condenser 86 and conductor 84 is connected to the transformer side of the. resistor '18, through the resistor 8l. Conductor 84 is also connected to the control grid 8| of tube B6, in series with the resistor 88. The output terminals B9 and 3| of the generator are connected respectively to the conductors 1'I and 1I), in. series with the variable resistor 92 and charge ing condenser 93. Condenser 53 is shown shunted by a resistor 94. The current supply transformer can be provided with a supplemental secondary 95 for supplying current to the cathode heaters o1' the tubes 68 and 89.

In one particular example the values of the resistors and condensers used in the pulse generator were as follows:

Resistor I8 4000 ohms Resistor 8l 2.5 megohms Fixed Resistor 82 0.3 megohms Variable Resistor 33 From 0 to 1 megohm Variable Resistor 92 From 0 to 500 ohms Condenser 8S 0.1 microfarad Condenser 93 16 microfarads Resistor 94 1 megohm.

-g In the foregoing example the solenoid coil I8' for the device I consisted ofv 1800 turns of No. 3l enamel insulated copper wire, the coil meas.- uring about 2 inches long and 3A inch outside diameter with sleeve I5 having an inside diameter of about 3/8 inch. l `In practice the parts of the generator as described above are mounted in a suitable enclosing box, with two controls for manual adjustment. One control serves to vary the value of resistor 92 and the other varies resistor 83. Adjustment of resistor 92 varies the amplitude or intensity of the pulses applied to the device I0, and adjustment of resistor 83 varies the frequency of the pulses.

. The generator described above is capableof supplying current having a wave form substantially as illustrated in Figure 4. It will be noted that the waveform is approximately saw-tooth, and that the pulses are spaced 1/2 cycle apart. In a typical instance the frequency of the pulses can be adjusted between 2O to 60 cycles per minute. At the beginning of a charging cycle, following firing of tube 66, a high voltage drop is applied across condenser 93 to charge the same, During this time condenser 85, which has been charged during the preceding firing cycle, is discharging through resistors 82 and 83. After full charging of condenser 93, the voltage drop across condenser 86 falls to a sufliciently low value t0 fire the tube 86. Firing of tube 66 causes `the plate-cathode impedance of the saine to be reduced to a low value whereby condenser 93 discharges through the same -to supply a current pulse to the output circuit. Discharging of condenser 93 causes simultaneous recharging of the timing condenser 86 whereby at the end of the discharging cycle the control grid of the tube 96 is biased suiciently negative to again block current from the rectifier.

Operation of the apparatus described above is as follows: Assuming that the generator is in operation and that the frequency and amplitude of the pulses are adjusted to be of desired values, current pulses are supplied to the winding I8 of the solenoid at recurrent spaced intervals. Assuming that the device I0 is being held in the hand of the operator, but that the tool 46 is not being pressed against the work, the rst current pulse received serves to move the magnetic plunger 2| forwardly to its limiting position, with the surfaces 39 and 4I in direct physical contact. Since the plunger 2I together with member 36 is made of ordinary steel, which will retain a substantial amount of residual magnetism during the intervals between pulses, the residual magnetism will serve to hold the plunger in a forward position as illustrated in Figure 3. Thus under such conditions the plunger does not reciprocate in response to the recurrent energization of the coil I8, and no blows are imparted to the member 43 or to the tool 46. Y

The operator now places the tool 46 against the work, which may be a tooth or other bone, and when it is desired to apply blows to the tool the operator presses against the work with sufficient force to cause the plunger to be forced rearwardly and separated from its magnetic attachment to the face 39. Immediately thereafter the plunger commences to reciprocate in response to the energizing pulsations. Thus when a pulse is received the plunger 2l is propelled forwardly to cause the pin 6I to strike a blow upon the pin 62, and thus apply an impact through the member 43 to the tool 46. Such impacts will continue as long as some-pressureis exerted by theoperator against the work. Immediately upon removing the tool 46 from the work, or when the operator ceases to apply any further pressure against the work, the plunger 2| again magnetically adheres or sticks to the end face 39 and is thereby made inoperative.

Either before or during operation of the plunger to apply impacts to the tool, the operator may adjust the pulse generator to vary the frequency of the pulses, or to vary the intensity of the blows. Adjustment of resistor 83 serves to vary thefrequency of the blows over a substantial range, while adjustment of resistor 92 serves to vary the amplitude or intensity of the blows.

In the foregoing description the pulse generator I I is adjusted in such a manner that between pulses the current flow drops down to a` relatively low value. `One relies entirely upon residual magnetism to hold the solenoid plunger 2l in forward inactive position. Generally, however, it is desirableto provide suflicient current ow between pulses to supplement the. residual magnetism and thus aid in retaining the plunger in its forward inactive position, Without however interferingv with normal reciprocation of the plunger. For the particular pulse generator described, holding current between pulses is provided by the charging current through condenser 93 supplemented by current ow through resistor 94, .and current iiow through resistance 94 by itself when condenser 93 has been charged. Increasedholding current can be Vprovided by reducing the value of resistor 94. In place of the pulse generator described above, various other types of electronic or gaseous tube generators can be used, which are capable of supplying unidirectional pulses at regularly spaced time intervals. It is also possible to provide mechanical devices for this purpose, as for example pulse generators of the vibrating contact or rotary commutator type.

It will be evident from the foregoing that our device has many inherent advantages. Electrical contacts within the device itself are totally eliminated, Blows 0r impacts are automatically applied when the operator applies pressure upon the work, and automatically cease when such pressure is removed; The operator can adapt the device for a wide variety of work by adiusting the freouency of the pulses and their amplitude.

We claim:

l. In a surgical mallet, a housing adapted to be held by an operator, an impact transmitting member slidably disposed within the housing, a tool mounting on one end of said member, an electrical solenoid coil carried by the housing, plunger means aligned with the impact transmitting member and movable within the solenoid coil to apply impacts to the impact transmitting member in response to current energization of the coil, and magnetic means for holding said plunger inactive when the operator fails to apply force to a tool carried by said mounting.

2. A surgical mallet comprising a housing adapted to be held by an operator, an impact transmitting member slidably disposed within the housing, a tool mounting carried by the outer end of said member, said thrust transmitting member being movable longitudinally of the handle between projected and retracted limiting positions, a solenoid coil carried by the housing and adapted to be energized by an independent source of recurrent electrical pulses. a magnetic eld lfor said solenoid coil including a plunger of magnetic material disposed in alignment with said impact transmitting member, said plunger being adapted to move to apply blows to the impact transmitting member in response to recurrent energization of the solenoid coil, and magnetic means for retaining said solenoid inactive in response to energizaticn of the coil with recurrent pulses, during periods when no force is being applied to a tool carried by said thrust transmitting member.

3. A surgical mallet as in claim 2 together with spring means serving to urge the impact transmitting member towards its projected position and serving to urge said, plunger in a direction away from said impact transmitting member.

A4. A surgical mallet as in claim 3 in which said spring means comprises a single spring have ing one end of the spring engaging said impact transmitting member and the other end of the same engaging said solenoid plunger.

5. In a surgical mallet adapted to apply recurrent blows to a surgical tool, a housing formed to provide a handle, a rigid impact transmitting member disposed within the handle and movable between limiting projected and retracted positions, a tool mounting on the exterior end of said member adapted to grip a surgical tool, a solenoid coil carried by the handle and adapted to be energized by an independent source of recurrent electrical pulses, a magnetic field for said solenoid coil including a plunger of magnetic material, said plunger being disposed within the coil and aligned with the impact transmitting member, the plunger being slidable from a rst limiting position to a second limiting position to apply an impact to said impact transmitting member, stop means for limiting movement of the plunger in a direction toward said impact transmitting member whereby movement of said plunger is confined between said rst and second limiting positions, spring means serving to urge the impact transmitting member toward projected position and serving to urge the plunger toward its 'first limiting position, said stop means including a member of magnetic material serving together with the magnetic material of the plunger to magnetically retain said plunger in said second limiting position when no pressure is being applied to a tool carried by the mounting.

6. A surgical mallet as in claim 5 in which said spring means is a single spring having one end of the same acting against said impact transmitting member and the other end of the same acting against said plunger.

JOSEPH J. NEFF. FRANK I. FULLER.

` REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

